Fibrous rubber product and process of producing the same



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higher temperatures may be used, particularly when vulcanized rubber is employed as is described below. The lower temperatures are generally preferred because of an increased stability of the sulphur chloride and because the plastic flow of the rubber at lowl temperatures is less and the true elongation attainable is consequently somewhat greater. The t-ime of vvulcanization shouldl bev suflicient to develop the full'` strength of the product, generally from live to fifteen, or twenty minutes, but ay prolonged exposure does no appreciable harm, since the rubber is apparently fully saturated with the vulcanizing agent in a short time, and `not 'subject to a further change. The vcharacteristic final properties of the product are not immediatelydeveloped, but apparentlya'equire a considerable period after exposure to the sulphur chloride.. The moist-ure of the .atmosphere seems to have some influence on the reaction, since the retractionof the vulcanized product on heating is greater if it is maintained in perfectly dryair. If desired, the vulcanized product may even be dipped in dilute ammonia solution, the water of which apparently assists in developing the properties characteristic ofv the product, while the ammonia serves to neutralize the4 acid which may be formed by decomposition of the sulphur chloride.

Calendered sheets of masticated rubber cannot be treated in the same manner as the unmasticated latex rubberv `described above, for the mastication destroys the resiliency .of the Irubber and makes it plastic, -so that no considerable true vreversible elongation is attainable. However, the mas- Ivticated rubber may be used ifits extensibility is restoredby vulcanization. Certain ingredients, particularly basic substances, .retardthe action of sulphur chloride, hence lthe time required for the treatment of ,stretchedjsoft vulcanized rubber must be separately determined for,` each different vulcanized composition. ,The preliminary vulcanization may be carried out by anyconvenient means, byv sulphur, eitherwith or without accelerators, or bysulphur chloride itself, but should be so regulated `as topermit a high degree of extension before 'the final treatment with sulphur chloride.

,i The rubber which is treated in accordance ,with this invention should be in sheets or strips sufficiently 'thin that the sulphur chloride may penetrate their entire thickness and effecta uniform vulcanization.V If ythe thickness greatly exceeds 0.01 inches the 'vulcanization tends to be superficial, with the center Aof the rubber still substantially unaffected.

The extraordinary results yattainable by meansof this invention may be illustrated by 4the lfollowing example, in which portions ef a sheet of unmasticated latex rubber are ythe vapor form elongations are shown 1n the following table.

Initial' Ultim-at 'Ultimate stretch sglglgh elongatlon Poun'dxper lPercent square inch. Percent 0 218 15 The products of this invention maybe used for any purpose for which flexible, fibrous substances have heretofore been used. The fibrous product maybe split into flat strips which can be Woven -into afabric, or the strips may be helically rolled tofproduce round threads which may be Woven, or built up into cords,or the product mayfeven be shredded Iinto individual fibers which may then be spun intovthreads, or mattedinto felts, or otherwise employed; y

The fibrous products kof this'invention are extremely resistant to corrosive chemicals, including all the common alkalies and acids with the exception of strong oxidizing acids, and are therefore particularly adapted to uses for which the ordinary textile iibersare unsuited because of their chemical reactivity. They do not deteriorate unduly with age, as does soft rubber vulcanized with sulphur chloride. However, their resist-ance to deterioration may be still further in creased by treating them with Vanti-('ixidants and anti-acids such as nitrogenous bases, in.-

cluding for example, ammonia', triethanolfamine, metaphenylene diamine, etc.

' rlhe sulphur chloridewhich is preferably employed in the ypractice of this invention ris the ordinary sulphur monochloride such Aas is used as a vulcanizing agent inthe. rubber industry.: Itis referably employedin ratier Vthan as a solution in an organic solvent, because of thedetrimental effectv of such solvents ,on gliiglily stretched: rubber. However, thel invention is not necessarily limited to this one vulcanizing agent, but other substances vcapable ota Atruevulcanization ofrubber to a compara'- -tively inextensible product, such as hydrogen persulphide or phosphorus sulphide, or l even elemental sulphur when used with-appropriate accelerators, may be substituted therefor. Substances which do not exert a true vulcanizing action, such as the lhalolgens, do not give rise to thek products herein f described.

Although a preferred method of, carrying Iout this invention hasbeendescribedin considerable detail, it is to be understood :that

the invention is not limited thereto, forthe f process described is susceptible of numerous l rubber, and vulcanizing the stretched rubber to a point at which it permanently retains the major part of its elongation together with the anisotropic structure imparted to it by the stretching.

2. The process which comprises stretching rubber to several times its original length, and vulcanizing the stretched rubber with a vulcanizingagent selected from the group consisting of compounds of sulphur with hydrogen, phosphorus, and chlorine.

3. The process which comprises stretching rubber to several times its original dimensions and vulcanizing it with sulphur chloride.

4. The process which comprises stretching rubber to an elongation just short of that at which it ruptures, and vulcanizing the stretched rubber in sulphur chloride vapor.

5. The process which comprises stretching unmasticated thin sheet rubber to an elongation just short of that at which it ruptures, and vulcanizing the stretched rubber in sulphur chloride vapor. f

6. The process which comprises stretching rubber a plurality of times to impart to it the maximum practicable elongation, and vulcanizing the stretched rubber with a cold vulcanizing agent to a point at which it permanently retains the' major part of its elongation together with the anisotropic structure imparted to it by the stretching.

7. The process which comprises stretching rubber a plurality of times in a single direction to impart to it the maximum practicable elongation, and vulcanizing the stretched rubber with a cold vulcanizing agent to a point at which it permanently retains the major part of its elongation together with the fibrous structure imparted to it by the stretching.

8. The process which comprises stretching rubber a plurality of times to impart to it vthe maximum practicable elongation, and

vulcanizing the stretched rubber in sulphur chloride vapor.

9. The process which comprises stretching rubber to several times its original length, vulcanizing the stretched rubber in sulphur chloride vapor, and subjecting the vulcanized stretched rubber to the action of moisture.

10. The process which comprises stretching rubber at least twice to impart to it the maximum practicable elongation, vulcanizing the stretched rubber in sulphur chloride Vapor, and subjecting the vulcanized stretched rubber to the action of moisture.

e'a'mmonia ,isolutionl if 11'. The .process Awhich :comprises :stretching rubber to several times itsuioriginaladimensions, 'vulcanizing f the rstre'tched'f ,rubber inf sulphur chloride i ',vapor, aandk ,immersing f'the'avulcanized #stretched rubber in aqueous K ,'5 12.- .The -zprocess which', comprises stretching A:rubberv Eto several times yfits f original 'dimensions, .vulcanizing :the stretched rubber lin su'lphurichloride vapor, vulcanized kstretched rubber wlith e a nitrogen'onsiibase.

y 13. The process which comprises stretching rubber a plurality of times to impart to it the maximum practicable elongation, vulf" canizing the stretched rubber in sulphur chloride vapor, and immersing the vulcanized stretched rubber in aqueous ammonia solution.

14. The process which comprises stretching rubber simultaneously in two directions perpendicular one to another, and vulcanizing the stretched rubber in sulphur chloride vapor.

15. An anisotropic vulcanized rubber '-'f characterized by high tensile strength and low ultimate elongation and retaining its anisotropic properties when heated to the temperature of boiling water.

16. A fibrous vulcanized rubber charac-f` terized by a high tensile strength and low ultimate elongation and retaining its fibrous structure after heating to the temperature of boiling water.

17. A ibrous vulcanized rubber characterized by a high tensile strength and low ultimate elongation and exhibiting a characteristic X-ray fiber diagram which is not destroyed by heating to the temperature of boiling water. i

18. A fibrous vulcanized rubber vulcanized by sulphur chloride and characterized by a high tensile strength and low ultimate elongation and retaining its fibrous structure after heating to the temperature of= boiling water.

19. A iibrous vulcanized rubber vulcanized by sulphur chloride and characterized by a high tensile strength and low ultimate elongation and exhibiting a characteristic X-ray fiber diagram which is not destroyed by heating to the temperature of boiling water.

20. A sheet rubber characterized by high` tensile strength and low elongation in its own plane, prepared by stretching thin.l sheet rubber in two directions perpendicular one to another and vulcanizing the stretched rubber in sulphur chloride vapor.

21. The process which comprises stretching rubber simultaneously in two directions andr vulcanizing the stretched rubber to a point at which it permanently retains the major part of its elongation together with.

1 and treating -;the f Vat Veo

-the anisotropic structure imparted toit by the stretching.

22.' An anistropic. sheet rubber characterized by high tensile Strength and 10W elongation in its own plane and retaining its anisotropic properties whenA heated to the temperature of boiiingwater, prepared by *stretching sheet rubber in two directions and vuicanizing the stretched rubber;

In Witness whereof I have Ahereunto set lmy hand this 13th day of June 1932.

WARREN F.Y BUSSE. 

